4D printing: The extra D is for self-assembleD

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3D printing is pretty easy to explain — normal printers work in 2D (length and width) while a 3D printer also handles height. To add height in any real sense you can’t just lay down more ink, you need an additive process that can actually build something, like meat or a gun. So when MIT’s Skylar Tibbits discussed 4D printing at TED this week (the video of the talk is not available yet), the obvious question was what’s the fourth dimension?

Usually the fourth dimension, when one is talking about such things, is time (at least when you are thinking in a non-Euclidean sense). When it comes to printing, 4D is when a 3D printed component is capable of self-assembly. As seen in the video below, a 3D-printed straw (let’s call it a pipe) is capable of folding itself into a cube. So, in a sense, the 4D still has to do with time, as the assembly happens over a given period after the printing is finished and the printed piece comes into contact with some sort of agent (in this case water).

Right now the folding process is done by combining a normal plastic with a reactive compound — a “smart material” — at the joints. The smart material contacts an energy source, such as water or one day it could be heat or electricity, and a change takes place. That change is set during the design process so it’s is both predictable and controllable. Based on the properties of today’s plastics it is probably not reversible.

The TED talk is not yet available and information about 4D printing is slim, especially about possible applications. On example — again having to do with straw-shaped objects — would be underground water pipes that expand when called upon to do so, rather then an entire section of roadway being dug up.

While the talk was at TED, the project resulted from a joint venture between 3D printing giant Stratasys, the Bio/Nano Programmable Matter Research Group at Autodesk, and MIT’s Self-Assembly Lab.